Conventionally, linear tape (e.g., LTO-4) has been organized as a single volume that is accessed from the beginning of the medium to the end of the medium. From the user conceptual perspective, a single volume linear tape is addressed and accessed via sequential logical blocks. A physical correlation between a logical block and a physical block(s) is provided by a device (e.g., tape drive) that provides access to the medium. While linear tape has provided advantages in many applications, it has typically not been employed with data de-duplication applications.
One skilled in the art knows that data de-duplication applications may produce fragmented data representations. Reconstituting an original data item (e.g., a file) from the fragmented data representation may involve random input/output (i/o) patterns that are unsuited to sequentially accessing linear tape. More generally, the random i/o patterns associated with data de-duplication have been problematic for sequential access storage devices.
Data de-duplication applications may also use multiple data structures (e.g., index, reconstitution recipes, catalogs) that grow at different rates and a repository of unique data blocks that may grow. The data structures store information related to the unique data blocks and to combinations of unique data blocks. These data structures and the repository may be continually growing and contracting in ways that produce random inputs and outputs to the media on which the structures are stored. Conventionally, sequential access storage media have had a single partition that made it difficult, if even possible at all, to accommodate these growing and changing data structures and their associated repository of unique data blocks. Thus, data de-duplication has typically not been supported with sequential access devices because it was difficult, if even possible at all, to arrange data structures and the underlying unique data blocks in an organization that provided practical utility for data de-duplication.
The foregoing statements are not intended to constitute an admission that any patent, publication or other information referred to herein is prior art with respect to this disclosure. Rather, these statements serve to present a general discussion of technology and associated issues in the technology.